High-speed fine grain light-sensitive material

ABSTRACT

A HIGH-SPEED FINE GRAIN SILVER HALIDE LIGHT-SENSITIVE MATERIAL FOR BLACK-AND-WHITE PHOTOGRAPHY, COMPRISING A SUPPORT HAVING SUPERPOSED THEREON AT LEAST TWO GELATINO-SILVER HALIDE PHOTOGRAPHIC EMULSION LAYERS, EACH OF SAID SILVER HALIDE EMULSION LAYERS CONTAINING AT LEAST ONE NONDIFFUSING COLOR COUPLER CAPABLE OF FORMING A DYE THROUGH THE REACTION WITH THE OXIDATION PRODUCT OF AN AROMATIC PRIMARY AMINO COLOR DEVELOPING AGENT, AND EACH OF SAID SILVER HALIDE EMULSION LAYRS BEING SPECTRALLY SENSITIZED TO SUBSTANTALLY THE SAME REGION OF THE SPECTRUM SELECTED FROM THE GROUP CONSISTING OF BLUE AND GREEN, BLUE AND RED, AND BLUE, GREEN AND RED, WHEREIN EACH OF SAID SILVER HALIDE EMULSION LAYERS HAS A DIFFERENT SPEED AND A DIFFERENT SILVER HALIDE-COUPLER MOLAR RATIO.

Oct. 3, 1972 I AKIRA KUMAI ETAL 3,695,882

HIGH-SPEED FINE GRAIN LIGHT-SENSITIVE MATERIAL Filed Aug. 5. 1970 FIG. I

x o o ODOVO 4 o o V o o o A O 04 b o AO Am vo o QA o b o v O O o V &

VO Vo ;b

//////// ///fl\ 5 "E FIG 2 O .Q V A O \oV A V-| INVENTORS AKIRA KUMAI TAKAAKI TERASHITA 5 A KM 'ATTORNEYS United States Patent O Japan Filed Aug. 3, 1970, Ser. No. 60,437 Claims priority, application Japan, Aug. 1, 1969, 44/60,806 Int. Cl. G03c 1 76 U.S. Cl. 96-68 6 Clains ABSTRACT OF THE DISCLOSURE A high-speed fine grain silver halide light-sensitive material for black-and-white photography, comprisng a support having superposed thereon at least two gelatino-silver halide photographic emulsion layers, each of said silver halide emulsion layers containing at least one nondifiusing color coupler capable of forming a dye through the reaction with the oxidation product of an aromatic primary amino color developing agent, and each of said silver halide emulsion layers being spectrally sensitized to substantally the same region of the spectrum selected from the group consisting of blue and green, blue and red, and blue, green and red, wherein each of said silver halide emulsion layers has a difierent speed and a different silver halide-coupler molar ratio.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to light-sensitive materials for black-and-white photography and more particularly, to high-speed fine grain light-sensitive negative materials for black-and-White photography, wherein two or more lightsensitive silver halide emulsion layers are superposed on a suitable support, each layer containing one or more non-diffusing color couplers and each being spectrally sensitized so as to have a sensitivity over a considerably wide region of the visible spectrum.

Description of the prior art For high-speed black-and-white negative camera films, gelatino-silver halide photographic emulsion layers have hitherto been usually used. On the other hand, low-speed light-sensitive materials used for rints, oice copies and printings have recently been replaced by those using a non-silver substance, for example, by photo-conductive substances, photosensitive polymers, vesicular films or diazo compounds, as is well known.

These new light-sensitive materials, in the latter case, are less expensive and capable of being finished more readily and rapidly, but, due to their low sensitvity, have not been put to practical use as camera films. The prior art gelatino-silver halide light-sensitive layers wherein fine silver halide grains are dspersed in gelatin are expensive considering the recent rise in the price of silver, since they must usually contain at least about 70 mg. per 100 cm. of expensive silver in order to give a maximum density necessary for good tone reproduction, and since only about one half of which remains as the final silver image, the other half being wasted away by fixing.

It is therefore an object of the present invention to produce a high-speed, fine grain photographic material for black-and-white photography.

Another object of the present invention is to produce a cheap black-and-white camera film wherein a smaller amount of silver halide is necessary.

Another object of this invention is to produce a photo- 3,695,882 Patented Oct. 3, 1972 graphic film which may be used in an ordinary camera whereby the photographer will get useful negatives, wherefrom fine grain black-and-white prints can be obtained.

Other objects will become apparent from the following detailed description of the present invention.

The present inventors have discovered a method for making a novel light-sensitive layer for black-and-white camera films having a finer grain size and a higher speed than that of the prior art wherein a negative image is made of only metallic silver obtained by reducing silver halide grains by a developer solution, whereby the abovementioned'minimum necessary quantty of silver can be reduced to about %a to M: that amount, and the cost of the film can thus be reduced largely.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAW'INGS FIGS. 1 and 2 are enlarged cross-sectional views of preferred embodiments of the high-speed fine grain lightsensitive materials according to this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the attachedl drawings, the light-sensitive material of the present invention comprises at least two silver halide emulsion layers. The material shown in FIG. 1 has two silver halide emulsion layers 1 and 2,

while that shown in FIG. 2 has three layers 1, 2 and 3. Each silver halide emulsion layer contains a color coupler 9, which will be described hereinafter.

The silver halide emulsions, together with a stabilizer such as 4-hydroxy-6-methyl-'1,3,3a,7-tetrazaindene, a hardener such as chrome alum, a coating aid such as saponin, and so forth, are uniformly coated onto a transparent support 8 such as glass, cellulose tiacetate or polyethylene terephthalate, the silver halide emulsions being spectrally sensitized to the same region of the spectrum by nfrared, panchromatic or orthochromatic optical sensitizing dyes well known to those skilled in the art (e.g., see Mees and James, The Theory of the Photographic Process, 3rd ed. (1966), Chapters 11 and 12) and having the desired spectral sensiti'vity characteristics so as to be sensitive, unlike the ordinary blue-sensitive yellow dye forming a layer of a color negative film not only to the blue light region to which the silver halide is sensitive, but also to the green, and/or the red light region of the visible spectrnm. This light-sensitive material may, in addition, have a antihalation layer 5, an intermediate layer 6 and a protective layer 7, according to methods well known in the art.

It should be noted that FIGS. 1 and 2 are given for purposes of illustration only and are not intended to limit the invention.

As the color-forming coupler for the novel light-sensitive material of this invention, the following may be used: benzoyl acetanilide, its substituted derivatives, and the like, known to those skilled in the art (e.g., see Mees and James, supra, Chapter 17) and, in many cases, the main spectral absorption of the dye o btained therefrom through color development exists mainly at the shorter wavelength region of the visible spectrum, the maximum absorption peak thereof being preferably within 400-530 nm.

These color-forming couplers may either be of a type (a) made non-difiusing by the attachment of ballasting groups such as about 12-18 carbon atoms in a chain, or their equivalents, and which are also made soluble in the aqueous gelatinous photographic emulsion by the introduction of hydrophilic groups such as -COOH or --SO H, or (b) of a non-diffusng type dissolved in a solvent, usually an ester such as triphenyl phosphate, tricresyl phosphate, dibutyl phthalate and dioctyl phthalate (see Mees and James, supra, p. 393, and U.S. Pat. No. 2,322,- 027). These couplers are often used in mixtures of two or more so as to improve the solubility of the couplers and the spectral absorption characteristics of the dye image formed by color development.

Examples of the former type are:

-(p-octadecaneamidebenzoylacetamido)isophthalic acid,

S-carboxy-Z-methoxy- (4'-octadecynylsuccinicmono amide) benzoylacetanilide,

2-(N-methyl-N-octadecyl-amino)-5-carboxy-(4-methoxybenzoyl)-acetanilide, and

2-(N-methyl-N-octadecyl-amino)-5-sulfo-(4-methoxybenzoyl)-acetanilide.

Examples of the latter type are:

4-benzoylacetamide-N-butyl-N-octylbenzamide,

benzoylaceto- (Z-methoXy-S-dodecyloxycarbonyl) anilide,

and,

benzoylaceto-Z-chloro-S-(Z-methylhexyloxycarbonyl)- anilide.

In addition, other couplers capable of giving a dye having a spectral absorption in a longer wavelength region of the spectrum may be used in this invention, for example, cyanoacetyl derivatives, dithio-l,3-diketones, oxythiazolyl- S-acetonitriles and 1-phenyl-S-pyrazolidones.

The light-sensitive material made by the present invention can of course be developed by ordinary black-andwhite developers after exposure, but is more preferably subjected to color development after exposure, in particular, color negative development, for example, to Fuji Film CN-l4 type processing or to Kodak C-22 processing. In this case, the above-mentioned coupler reacts with the oxidation product of the aromatic primary amino color developing agent to give a color dye image depending on the quantity of exposure (see Mees and James, sup'a, Chapter 17).

Since there are a large number of color processing laboratories at present, one can have the foregoing lightsensitive material color processed readily and correctly within a short time after exposure.

In the foregoing light-sensitive layer, through ordinary color negative processing, the silver image is completely removed during the bleaching step and only the negative dye image remains.

The novel characteristics of this dye image consist of the following four points:

(1) The graininess of the negative dye image can be made much finer than that of the silver negative image obtained by ordinary black-and-white development by selecting the molar ratio of silver halide to the coupler to be a suitable value in each emulsion layer, for example, 40 in the high-speed upper layer 1 of FIG. 1, and 20 in the low-speed lower layer 2, and by suitably selecting the thickness of each emulsion layer. Generally, the silver:coupler molar ratio may vary in the upper layer from to 80, and in the lower layer from 5 to 30. The thickness of each layer may vary from 1.5 to 4 microns.

(2) A positive picture can readily be made from the negative dye image -by printing the latter on an ordinary blue-sensitive or blue-green sensitive black-and-white printing paper, positive film and other various light-sensitive materials having a spectral sensitivity within a region of 300 to 550 nm.

(3) The spectral absorption of the dye image can easily be varied to a certain extent by changing the structure of the coupler or by using a mixture of two or more couplers having different spectral absorption characteristics, so as to match the absorption to the spectral sensitivity characteristics of the particular sensitive material used for printing.

(4) Under practical conditions, the coating quantity of silver halide grains necessary to give the same maximum density in H-D curve is, in most cases, about %i to A times as much as that of ordinary black-and-white film, as will be apparent from the following examples. Generally, the emulsions contain from 10 to 50 mg. of silver per cm The advantage to be particularly emphasized is characteristic number 1. In ordinary black-and-white film, the coarsening of the silver halide emulsion grains for the purpose of raising the photographic sensitivity, leads to a deterioration of the graininess of the final negative silver image, while, in the light-sensitive material of the present invention, the graininess of the dye image obtained by color development, being constituted of dye images of two or more layers, is not simply proportional to the size of the silver halide grains or to the "graininess" of the silver image obtained therefrom and a fine graininess" negative can be obtained in spite of the high-speed. That is to say, the light-sensitive material of the present invention has surprisingly two contradictory characteristics, i.e., high-speed and fine "graniness," which are most desirable for camera films.

Furthermore, as mentioned in characteristic number 4 above, the necessary coating quantity of silver can be greatly reduced as compared with ordinary high-speed light-sensitive negative materials for black-and-white photography, and the requirements on the spectral adsorption characteristics of the developed color image are not so severe as in the case of ordinary color negative film. consequently, the production cost of the lightsensitive material of the present invention is reduced as a whole by selecting a very inexpensive color-forming coupler, and one is able to take inexpensive high-speed and fine graininess` black-and-white pictures even considering the increased cost due to the necessity of color development in place of the more simple black-and-white development.

Furthermore, the present invention is advantageous in the conservation of valuable silver sources, since all the silver existing in the light-sensitive material is dissolved in the color processing baths followed by recovery and regeneration, unlike the case of ordinary black-andwhite films.

Since the yellow dye negative image made by the method of the present invention is not so visible under a usual green or red safelght for darkrooms and since this is inconvenient for the preparation of prints, a small quantity of a coupler capable of forming a dye image of magenta or cyan color (see Mees and James, supra, Chapter 17) can be used, together with the yellow-forming coupler, as the occasion demands, in order to overcome this disadvantage.

The present invention is described in greater detail by the following examples, which are merely illustrative, and not intended to limit the present invention in any manner.

EXAMPLE 1 (a) A solution of 44.6 grams of a yellow-forming coupler, 4 benzoyl acetamide N butyl N octylbenzamide in 30 ml. of dibutyl phthalate and 45.0 ml. of ethyl acetate was added to ml. of a 10 weight percent aqueous gelatin solution together with 300 ml. of a 10 percent aqueous solution of sodum dodecylbenzene sulfonate. The whole mxture was passed through a colloid mill several times. In this way, a very stable and very fine emulsion was obtained which was added to 1,000 grams of a fine grain low-speed gelatino-slver halide emulsion, containing 1 mole of silver halide con- &695382 sisting of mole percent silver iodide and 95 mole percent silver bromide, and 80 grams of gelatin, and was preliminarily digested with a sulfur sensitizer and a gold sensitizer to obtain maximum speed. To the resultant mixture were then added 100 ml. of a 0.1% methanol solution of anhydro 5,5',6,6' tetrachloro 1,1' diethyl- 3,3' di(4 sulfobutyl benzimidazolocarboeyanine hydroxide and 80 ml. of a 0.025% methanol solution of anhydro 1,1' di(4 sulfobutyl) 2,2' cyanne hydroxide as optical sensitizing dyes, 15 ml. of a 1% aqueous solution of 4 hydroxy 6 methyl 1,3,3a,7 tetrazaindene as a stabilizer (i.e., as an antifoggant), 1.5 ml. of a 10% aqueous solution of chrome alum as a hardener and 1 ml. of a 6% aqueous solution of saponin as a coating aid, and the resulting mixture was uniformly coated onto a cellulose triacetate film base followed by drying to give a dry emulsion layer having a thickness of 2.4 (The molar ratio of silver halde to color coupler is 10 (mol percent).)

(b) To a coarse grain high-speed gelatino-silver halde emulsion containing 1 mole of silver halde, consisting of 5 mole percent silver iodide and 95 mole percent silver bromide, and 200 g. of gelatin, and digested with a sulfur sensitizer and a gold sensitizer to obtain maximum speed, were added an amount (one third by weight) of the aforesaid emulsion containing the yellow-formiug coupler of (a), a sensitizing dye, a stabilizer, a hardener and a coating aid as in (a) and the whole mixture was coated onto the layer (a) to a dry thickness of 2.6n, onto which a gelatin protective layer of about ly. in thickness was further coated. (The molar ratio of silver halde to the color coupler is 30 (mole percent).)

(c) A high-speed black-and-white negative film used as control was obtained in like manner by applyiug a mixture of the same high-speed gelatino-silver halde emulsion, sensitizing dye, stabilizer, hardener and coating aid as those of (b), except that the emulsion containing the yellow-forming coupler was omitted, to a cellulose acetate film base followed by drying to give a dry emulsion layer having thickness of 14u. The same protective layer as that of (b) was then applied thereon.

The speed and the dry thicknesses of the layers (a) and (b) were selected so that the printing density of the yellow dye image of the superposed film of (a) and (b) obtained by processing with Kodak C-22 processing, on Fuji Bromide No. 3, a black-and-white printing paper for enlarging, was the same as the printing density of the silver image (c) obtained by 7 minutes development with Kodak D-76 developer. The quantity of coated silver and photographic characteristics are shown in Table '1, and the Selwyns granularity values (G-value), in Table 2.

As is evident from the foregoing results, the film of the present invention, (a) and (b), has an almost equal speed and a much better coefiicient of Selwyfs granularity using an amount of silver of about one third that used in film (c) of the prior art.

EXAMPLE 2 (a) To 1 kg. of a medium-speed fine grain silver iodobromde emulsion, containing 9.8 weight percent of gelatin and 2.4 weight percent of silver as silver halde (6 mole percent silver iodide), were added ml. of a 0.05 percent methanol solution of 3,3'-diethyl-9-methylthiacarbocyanine bromide and 3.0 ml. of a 0.1 percent methanol solution of 3,3,9-triethyl-5,S-diphenyl-oxacarbocyanne rhodanide as optical sensitizng dyes, 10 ml. of a 1% aqueous solution of 4-hydroxy-6-methyl-1,3,3a-7- tetrazaindene as an antifoggant, 200 ml. of a 10% alkaline aqueous solution of 5 (p octadecaneamidebenzoylacetamide) isophthalic acid as a yellow-forming coupler, a hardener and a coating aid, and the whole mixture was coated onto a cellulose triacetate film base followed by drying to obtain 1. 02 g. of silver per one square meter. (The molar ratio of silver halde` to the color coupler is 6.3 (mole percent).)

(b) To a high-speed silver iodobromide emulsion, containing 8 weight percent gelatin and silver halde corresponding to 3-weght percent of silver (silver iodide: 4 mole percent), were added 70 ml. of a 10% aqueous alkaline solution of the above mentioned yellow-forming coupler and the above mentioned spectral sensitizing dyes, stabilizer, hardener and coating aid and the whole mixture was coated onto layer (a), to give 1.08 g. of silver per one square meter, onto which an ordinary gelatin protective layer of about I in thickness was then coated. (The molar ratio of silver halde to the color coupler is 18 (mole percent).)

The speed of the two emulsions and the thickness of layers (a) and (b) were so selected that the printing density of the dye image of the superposed film (a) and (b), obtained by processing with Fuji Film CN-l4 processing, on Berona No. 3, a black-and-white printing paper for enlarging, was the same as that of the printing density of the silver image obtained by eight minutes' development with Kodak D-76 developer, on the above-mentioned printing paper.

The amount of silver coated and the photographic characteristics of the superposed film of the present invention and the black-and-white control film are shown in Table 3 and the Selwyn's granularity values (G-value) are shown in Table 4.

What is claimed is:

1. A high-speed fine grain silver halde light-sensitive material for black-and-white photography, comprising a support having superimposed thereon at least two gelatinosilver halde photographic emulsion layers, each of said silver halde emulsion layers containing a nondiffusing yellow color coupler capable of forming a dye through the reaction with the oxidation product of an aromatic primary amino color developing agent, and each of said silver halde emulsion layers being spectrally sensitized to substantially the same region of the spectrum selected from the group consisting of blue and green, blue and red, and blue, green, and red, wherein each of said silver halde emulson layers has a different speed and a different silver halde-coupler molar ratio.

2. The silver halde light-sensitive material as in claim 1, wherein said gelatino-silver halde photographic emulsion layers of different speeds are successively coated ou said support in such an order that the emulsion layer of higher speed is disposed further from the support than the layer of lower speed.

3. The silver halde light-sensitive material as in claim 1, wherein said gelatino-slver halide emulsion layers of different silver halde to color coupler molar ratios are successvely coated on said support in such an order that the emulsion layer of larger molar ratio is disposed further from the support than the layer of lower molar rato.

4. The silver halide light-sensitive material as in claim 1, wheren the silver halde emulsions each contain at least a non-difiusng yellow coupler.

5. A print of the original of claim 1.

6. The silver halde light-sensitive material as in claim 1, wherein the silver halde emulsion layer contains a sufficient quantity of a coupler capable of forming a dyeimage of magenta or cyan color as serves for said dyeimage to be visible to the naked eye under a safe light for darkrooms.

References Cited UNITED STATES PATENTS 5/ 1945 Wilder 96-74 4/ 1964 Hellmig 96-68 7/ 1964 Hellmig 96-68 6/ 1969 Wychof 96-68 4/1970 Beckett 96--68 FOREIGN PATENTS 8/ 1959 Great Britain 96-74 NORMAN G. TORCHIN, Prmary Examiner I. R. HIGHTOWER, Assistant Examiner U.S. Cl. X.R. 

